1. Field of the Art
The present invention relates to image forming apparatuses used to transfer a toner image to paper sheets, thereby forming a visible image thereon.
2. Background of the Prior Art
Conventional image forming apparatuses of this type include the so-called electronic copying machines, laser printers, etc. These apparatuses are provided with a photosensitive drum, for use as an image carrier, an apparatus body for forming an electrostatic latent image on the drum, and a developing device for supplying a toner to the latent image, thereby developing the image. Developing devices of the so-called cassette type have recently started to be used. These developing devices, are formed independently of the apparatus body and are adapted to be removably attached to a mounting portion of the body by one-step operation.
When using one such cassette-type developing device, it must be located accurately in position. The reason is that if the distance between the photosensitive drum and a developing roller for supplying the toner is only a little longer than a predetermined distance, the toner sometimes cannot be supplied fully to the drum, thus failing to providing a clear image. If the developing roller is located too close to the drum, on the other hand, the toner will be supplied excessively, and in an extreme case, the delicate photosensitive drum will possibly be damaged.
Meanwhile, the developing device is provided with connectors through which signals for controlling the drive of a developer feed roller or the toner content of a developing agent are transferred for output or input. After the developing device is attached to the mounting portion of the apparatus body, the connectors, fixed individually to the body and the developing device, are connected manually to each other.
If the developing device is not located in its correct position or is tilted an operator sometimes may couple the connectors without noticing the situation. In such a case, the image obtained may be defective and the apparatus may be damaged.
Moreover, the operator may commit a wrong operation such that the developing device is mounted without connecting the connectors.